Notes regarding transcriptions and subtitles
Deaf users and users who are hard of hearing cannot use audio content of videos at all or only to a limited extent. Blind users or users with very low vision cannot perceive visual content of videos at all or only to a limited extent. Therefore, you should create an audio description/transcript of the visual content of each video or text-based alternative content and always include
subtitles!
Subtitles can also be helpful for other users, e.g. when they are watching in noisy surroundings or if they have a different native language.
Subtitles/text-based alternatives are only necessary if the video itself is not already an alternative medium.